A sensor network technology that senses and controls an external human environment has recently emerged as a core technology. That is, a USN has attracted attention to sense objects and environments by attaching electronic tags to all objects and build and utilize real-time information about the objects and environments over a network. The USN has evolved from its initial stage of identifying an entity using an electronic tag through a stage of acquiring environmental information simultaneously by adding a sensing function to a stage of controlling tags by configuring an ad-hoc network so that tags may communicate with one another. Further, the recent years have witnessed the development of the USN toward an IP-USN in which one or more IP-based sensor nodes are networked. It is expected that the USN will be developed more rapidly.
In fact, the information and communication infrastructure policy working group of the Ministry of Information and Communication reported that the global market of the USN would grow from about 600 million dollars in 2006 to about 12.8 billion dollars in 2012, representing an annual growth of 66%. The domestic market of the USN is expected to grow 71% annually, starting from 2008, the year when USN services were actually deployed, and thus reach 2,100 billion wons in 2012.
A sensor network is considered to be a base technology for constructing a ubiquitous computing environment. The sensor network includes an RFID/sensor node being a small-size radio transceiver equipped with sensing and communication functions, a sink node for collecting sensed information from the sensor node or transferring event data to an external device, and a reference node for transmitting its current location information to a neighbor node with a predetermined power at every predetermined interval. Compared to a conventional network, this sensor network basically seeks to collect remote information automatically, not to communicate. As a core technology of the ubiquitous environment, the sensor network finds its applications in a wide range of fields including target tracking, environment monitoring, traffic information management, logistics management, etc. and it also has potentials to be applied to many other fields.
However, a current sensor network that operates in compliance with Institute of Electrical and Electronics Engineers (IEEE) 802.15.4 Low Rate-Wireless Personal Area Network (LR-WPAN) and ZigBee standards uses an independent 16-bit or 64-bit address system as the address of an RFID/sensor node, instead of an IP address. Hence, the current sensor network is configured as a stand-alone network without being connected to an IP network.
The 6LoWPAN standard was developed as one of approaches to interaction between the Internet and the RFID/sensor network. However, this technology requires an IP version 6 (IPv6) layer and a 6LowWPAN adaptation layer in an RFID/sensor node having resource-limited characteristics such as the requirements of low energy, low processing power, low data rate, etc. The resulting large processing load leads to increased energy consumption.